Designing the Interface Layer of Solid Electrolytes for All-Solid-State Lithium Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Solid-State Chemistry

Background:

• Lithium aluminum titanium phosphate (LATP) is a promising solid-state electrolyte (SSE) for all-solid-state lithium batteries (ASSLBs) due to its high ionic conductivity and stability.
• However, poor interfacial contact and slow lithium-ion migration at the Li/LATP interface hinder practical applications of ASSLBs.
• Developing effective strategies to improve the Li/LATP interface is crucial for advancing ASSLB technology.

Purpose of the Study:

• To design and fabricate a composite ion-conducting layer at the Li/LATP interface to overcome interfacial limitations.
• To investigate the effect of the MoS₂@SP protective layer on lithium-ion migration and interfacial contact.
• To evaluate the electrochemical performance of ASSLBs incorporating the modified LATP electrolyte.

Main Methods:

• Chemical vapor deposition (CVD) was used to construct a MoS₂ film on LATP.
• A solid polymer (SP) liquid precursor was introduced to form a MoS₂@SP protective layer.
• Electrochemical impedance spectroscopy (EIS) and battery cycling tests were performed to assess ionic conductivity and stability.

Main Results:

• The MoS₂@SP layer effectively reduced the Li-ion migration energy barrier and enhanced Li-ion adsorption.
• The Li symmetric cell with LATP-MoS₂@SP demonstrated stable cycling for over 1200 hours at 0.1 mA cm^-2.
• The full cell (LiFePO₄ cathode) exhibited 86.2% capacity retention after 400 cycles at 1 C.

Conclusions:

• The developed MoS₂@SP composite layer significantly improves interfacial properties of LATP SSEs.
• This strategy enhances interfacial ion transport and contact, leading to high-performance and stable ASSLBs.
• The study presents a viable design approach for overcoming interface instability in SSEs for next-generation batteries.